High resolution two dimensional electrophoresis allows a large fraction of the estimated 30,000 to 50,000 human proteins to be identified by map position and to be quantitated. Normal and cancer cells have been mapped in orienting studies and many differences found. To give meaning to these results, and to systematically exploit them, a large data base (the Cancer Protein Data Base) including all available and all obtainable data on each spot is required, with the data base directly linked to CRT map displays. The data base will include (for each protein) intracellular location, types of cells in which found, names, functions, disease correlations, biophysical data, literature citations, membership in coregulated sets, differentiational stage of occurrence, and chromosomal location of the coding gene. The theses to be explored are that cells are highly integrated systems to be understood in terms of protein sets and the regulational circuits involving them, and that compositional changes in cancer cells are not random, but reflect alterations in normal regulational and differentiational functions. This Phase I proposal is for the continued development of the TYCHO and KEPLER data base systems, specifically directed to cancer studies, in a private setting.